Estudio ecográfico longitudinal de la degeneración de la estructura muscular en pacientes con esclerosis lateral amiotrófica

Resum

Objectives. 1. To assess the capacity of new muscle ultrasound markers based on morphotextural analysis as a tool of discrimination between patients with amyotrophic lateral sclerosis (ALS) and healthy control groups. 2. To analyze the ability of new muscle ultrasound markers based on a morphotextural analysis to monitor ALS patients Methods. This study was approved by the Ethics Committee of the Universidad Católica de Murcia (Spain) and registered at ClinicalTrials.gov (NCT02507713). All participants provided written informed consent. Patients were recruited from the ALS Association (ADELA) of Valencia (Spain) between September 2013 and April 2014. Twenty-six patients diagnosed with ALS according to the revised El Escorial Criteria by an experienced neurologist were included. The same cohort was used previously to assess changes in muscle thickness (MTh), echointensity (EI), echovariation (EV) and textural parameters obtained from gray level co-ocurrence matrix (GLMC) between ALS patients and 26 healthy controls. For this longitudinal study, each patient was evaluated twice more with an interval of 10 weeks ± 7 days. Demographical and clinical characteristics (sex, age, weight, height, body mass index, time from diagnosis) were recorded. Muscle strength was measured using the Medical Research Council (MRC) global score with a maximum value of 100 and segmented by upper (max. 50) and lower limbs (max. 30) and neck muscles (max. 20). The ALSFRS-r rating scale was assessed by the same investigator on the same day as the muscle ultrasound was performed. Muscle ultrasound was performed in four muscle groups of each side by the same experienced examiner, with a phased array real-time scanner LOGIQe BT12 (General Electric Healthcare, Beijing, China) with a linear array transducer (12L-RS; 5-13 MHz). We applied a standardized protocol with bilateral transverse ultrasound images of the biceps/brachialis, forearm flexors, quadriceps femoris and tibialis anterior groups were obtained and measured. Three images were taken of every muscle in order to minimize error in measurement parameters. Once the images were obtained, classified and analyzed with the Image J software (v.1.48 [2015], National Institutes of Health Bethesda, MD, USA), EI, EV ultrasound parameters and GLCM textural features were obtained. Results. The patients showed a time of evolution since diagnosis of 16.3 (9.89, [13.5-19.1]) months. Patients started the study with a score of 26.2 (11.67; [22.9-29.4]) points for ALSFRS-r scale and 58.5 (24.75; [7-65.4]) points for MRC (max. 100 points). The MTh, EI and EV ultrasound parameters showed a high discriminatory capacity: with a lower MTh , a higher EI and a lower EV (less granularity, more homogeneous) in ALS patients. Regarding the variables obtained from the GLCM textural parameters presented different behaviors depending on the muscle groups studied, but in combination with the EV, they discriminated more accurately than the usual ultrasound parameters of MTh and EI. After a follow-up period of 20 weeks, a loss of muscle strength, a decrease on the ALSFRS-r score and MTh and an increase in the EI were observed. A tendency to increase the muscle heterogeneity was observed for the EV and GLCM textural parameters. Conclusions. In addition to the ultrasound parameters usually studied, EV and GLCM textural parameters have shown a high discriminatory capacity between ALS patients and healthy control groups. Quantitative muscle ultrasound may be more sensitive than clinical parameters to monitoring ALS patients. In the progression of ALS, a loss of MTh and an increase of muscle EI and heterogeneity were observed. The changes in the muscle texture vary depending on the muscle group and the phase of involvement so they may be correlated with the different states of muscle denervation.